Two varieties of orbital palm sanders are typically encountered, namely a random orbit type of orbital sander (hereafter random orbit sander or ROS) and a quarter-sheet type of orbital sander (hereafter quarter-sheet sander or QSS). Each type has a motor connected to a power-transmission. A two-part clam-shell-type field housing contains the motor and a two-part clam-shell-type shroud contains the power-transmission.
Due to the different types of oscillation exhibited, the ROS and QSS power transmissions differ. Similarly, the ROS and QSS motors differ. As a result, the field housings for the RSS and for the QSS differ. And the shrouds for the RSS and the QSS differ.